Fluid streams such as liquid flows and gaseous flows (e.g. air flows) often carry particulates that are often undesirable contaminants entrained in the fluid stream. Filters are commonly employed to remove some or all of the particulates from the fluid stream.
Seals such as o-rings are often provided to seal the filter to a surface of a filter housing, or to an inlet or outlet pipe, which carries the contaminated fluid or gas into or out of the filter. This sealing relationship helps prevent unfiltered fluid from bypassing the filter. Often, an imperfectly manufactured filter housing or pipe will have a sealing surface that is out of round or out of tolerance, thus making it more difficult for the seal to provide a full sealing relationship, and increasing the likelihood that contaminated fluid can bypass the filter. As such, filter housing makers will often attempt to tightly tolerance their sealing surfaces on housings. However, if that is not done, then a problem exists as typical O-ring gaskets can have sealing problems and therefore allow some leakage if the sealing surface is even 0.0005 inches out of round, or has an actual diameter even 0.010 greater than a design diameter. O-ring gaskets are also known to allow leakage if the sealing surface has a roughness of approximately 32 micro-inches or greater.
The invention provides improvements over the prior art relating to seals for filters. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.